ABSTRACT This paper discusses how exergy efficiency can help generate insight into effective and ineffective temperature combinations for heat exchange at near-environmental temperatures. The analysis uses exergy and energy efficiencies@ combined with exergy consumption@ warm/cool exergy and a dimensionless temperature@ to gain insight into the effect of varying temperatures in air-to-air heat exchange at near-environmental temperature. The analysis is performed with a simple model for an air-to-air sensible heat exchanger. The paper presents an example of how the approach can be used as a basis to select exergy efficient temperature combinations when conceiving heat exchange in building ventilation.